Circuit breaker



Nov. 2, 1954 A. R. CELLERINI ETAL CIRCUIT BREAKER Filed June 18, 1952 INVENTORS Albert R.Cellerlni and Joseph A.Drobney. @fix/ ATTORNE Fig.l.

WITNESSES:

United States Patent CIRCUIT BREAKER Albert R. Cellerini, Beaver, and Joseph A. Drobney, Duquesne, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pin, a corporation of Pennsylvania Application June 18, 1952, Serial No. 294,184 14 Claims. (Cl. 200-88) This invention relates to circuit breakers and, more particularly, circuit breakers which are manually operable to open and close the circuit and which are automatically operated to open circuit in response to abnormal conditions.

An object of the invention is to provide a circuit breaker in which a switch member is biased by two springs one of which overcomes the other to hold the switch member closed and having a trip device operable to reduce .the bias of one spring to permit the other spring to move the switch member to open position.

Another object of the invention is to provide a circuit breaker having a switch member biased at both ends about an operating lever by a pair of springs one of which is normally stronger than the other, the stronger spring being attached to a releasable member which, when released, reduces the bias of said "stronger spring to a point where the other spring actuates the switch members to open positions.

Another object of the invention is to provide a circuit breaker having a switch member biased to closedposition by a spring which is controlled by a trip device operable in response to abnormal conditions to reduce the bias of the spring to permit another spring to move the switch member to open position.

The invention, both as to construction and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read .in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is an elevational view of the circuit breaker with the cover broken away and partly .in section, the parts being shown in .full lines in the closed position.

Fig. 2 is a view similar to Fig. 1 but showing the circuit breaker in the tripped open position.

Referring to the drawing, the circuit breaker comprises a housing 11 and a-cover plate 13 both -of molded insulating material, a stationary contact 15, a cooperating movable contact 17 mounted .on a movable contact bar as switch member 19, an operating lever '21 and a trip device indicated generally at 23. The stationary contact 15 is mounted on the inner end of a conductor 25 which extends out through a suitable opening .in the adjacent end wall of the housing '11 .and has a terminal connector 27 attached to its outer end. The end of the movable contact bar 19 is connected by a flexible conductor 29 to the free end of a bimetal element 31 which has its other end rigidly mounted on .the inner end of a conductor 33. The conductor 33 extends out through an angular opening in the adjacent end wall of the housing 11 and has a terminal connector 35 mounted on its outer end. The conductor 33 is rigidly secured to the housing 11 by a screw '36. j

The operating lever 21 is constructed of molded insulating material and is provided with trunnions 37 molded integral therewith which .pivotally' engage in companion openings in the side wall of the housing 11 and the cover plate '13. The operating lever '21 is provided with an integral finger piece 39 extending outwardly through an opening 41 in the housing 11 for manual operation of the lever 21. The inner end of the open ating lever 21 is slotted .as at 43 and legs 45 (only one being shown) formed by slot straddle this .contact bar 19 to prevent lateral movement thereof. The bottom of the slot43 .is formed into two spaced projec- ,cam-s the contact bar downwardly to the closed 2,693,513 Patented Nov. 2, 1954 tions 47 and 49 for engaging and controlling the operation of the contact bar 19. The projections 47 and 49 are adapted to engage respectively raised surfaces 51 and 53 on the contact bar 19. A pin 55 in the contact bar 19 adjacent he right-hand end thereof engages in arcuate slots 57 in the side wall of the housing 11 and in the cover plate to guide the contact bar 19 and prevent longitudinal movement thereof.

This contact end of .the contact bar 19 is biased in opening direction by an opening spring 59 tensioned between the contact bar and a pin 61 in the side wall of the housing 11, and the opposite end of the contact bar 19 is biased to closed position by a closing spring 63 connected under tension between the contact bar 19 and a pivoted releasable trip member 65. The releasable trip member 65 is pivotally supported on a pin 67 mounted .in the side wall of the housing 11 and the cover plate 13. The releasable member 65 normally engages the free end of the bimetal element 31 to releasably restrain the releasable trip member 65 in the position shown in Fig. 1 wherein it maintains the spring 63 under a .predetermined tension. In the closed position of the parts, as shown in full lines in Fig. l, the contact bar pivots on projection 47 (there being a slight space between the pin 55 and the top of the slot 57) and spring 63 is considerably stronger than the spring 59, or at least exerts more torque on the contact bar 19, thus maintaining the contact bar 19 in the closed position and providing contact pressure. In this position, the spring 63 overcomes the tension of the spring 59 and biases the contact bar 19 counterclockwise to the closed position about the projection 47 on the operating lever 21.

The circuit breaker is manually opened by clockwise movement of the operating lever 21 from the on position to the off position as shown in Fig. 1. During this movement of the operating lever, the projection 47 on the operating lever passes to the left of the raised surface 51 of the contact bar 19 permitting upward and opening movement of the contact bar. During the early part of this movement, the pin 55 moves up to engage the upper end of the slots 57 which, as will be obvious, greatly increases the moment arm with which the force of the spring 59 is applied to the contact bar. The result is that the spring 59 is able to apply a relatively greater torque to the contact bar than the spring 63 which at this time has a very small moment arm, consequently the spring 59 overcomes the spring '63 and moves the contact bar 19 to the open position shown by dot and dash lines in Fig. 1. During the opening movement, the contact bar 19 pivots about the pin 55 at the upper end of the slot 57 until a low portion 69 on the upper edge of the contact bar 19 between the raised surfaces 51 and 53 engages the projection 49 on the operating lever 21.

The contacts are closed by reverse manipulation of the operating lever 21 from the off to the on position. During this movement of the operating lever, the projection '47 on the operating lever acts on the surface of the contact bar 19 between the points 69 and 51 and position. During this movement the moment arms with which the springs 59 and 63 apply their forces to the contact bar change so that the spring 63 again applies the greater torque and overcomes spring 59 and rotates the contact her counterclockwise about the projection 47 to the closed position.

The circuit breaker is tripped open automatically by operation of the trip device 23. The trip device comprises the bimetal element 31, electromagnetic trip means including an armature 71 rigidly mounted on the bimetal element and asma'gnet yoke 73 supported in the end wall of the housing 11 adjacent the trip device.

Upon the occurrence of an overload circuit below a predetermined value of, for instance, ten times normal rated current, the bimetal becomes heated in response to the flow of excessive current and, when heated a predetermined amount, deflects toward the right and releases the trip member 65. When the releasable member 65 is released the spring 63 moves it to the position shown in Fig. 2, which results in reducing the tension of the spring 63 .to a point where it is overcome by the spring 59 which rotates the contact bar 19 about the projection 47 in opening direction. During the opening movement of the contact bar 19, the raised portion 53 engages the projection 49 on the operating lever 21 and moves the latter to an intermediate trip indicating position where the handle is stopped by engagement of projection 75 with a tail 77 on the trip member 63. The parts are shown in Fig. 2 in the tripped open position. In this position, the effective forces of the springs 59 and 63 are substantially balanced and these springs bias the contact arm 19 into engagement with both of the projections 4-7 and 49 on the operating lever.

Before the contacts can be closed following an automatic tripping operation, it is necessary to first reset and relatch the trip member 65 in order to restore the normal tension or' the spring 63. This is accomplished by moving the operating lever 21 from the trip position (Fig. 2) to the off position (Fig. 1) during which movement a projection 75 on the lever 21 engages the tail 77 on the trip member 65 and rotates the trip member to the position shown in dot and dash lines in Fig. 1, the latch end of the trip member wiping by the bimetal element 31 which, due to its inherent resiliency, resumes its latching position under the trip member 65. When the operating lever 21 is moved from the trip position (Fig. 2) to the ofi position, as shown by dot and dash lines in Fig. l, the projection 47 on the operating lever 21 is moved to a position above the low point 69 on the contact bar, permitting the springs 59 and 63 to move the contact bar 19 to the open position shown in dot and dash lines in Fig. l. The contacts are then closed in the previously described manner by movement of the operating lever from the off position back to the on position.

The breaker is tripped open instantaneously in response to overload currents above the predetermined value of, for instance, ten times normal rated current, or a short circuit current, by the action of the electromagnetic trip means I' l73. When such an overload occurs, the electromagnet '71-'73 is energized by the flow of excessive current through the bimetal element 31 and the armature "ll is attracted toward the magnet yoke 73. This binds the bimetal element against its normal bias and effects release of the trip member 65 whereupon the circuit breaker is automatically opened in the manner previously described in connection with the description of the thermal tripping operation.

Following an automatic, instantaneous tripping opertact ,to open and close the circuit, an operating lever movable to effect opening and closing movement of said ation, the trip member 65 is reset and the contacts are 1 closed in the previously described manner.

Means is provided to adjust the trip device to vary the tripping point of the breaker. This means comprises a round-headed screw '79 thrcadedly engaging the lower inner end of the conductor 33, at the point Where the bimetal element 31 is secured thereto, and having its rounded head seated in a concave recess in the adjacent end wall of the housing 11. An access opening 81 is provided in the housing to permit the insertion of a suitable tool in order to adjust the screw 79. By rotating the screw 79, the inner end of the conductor 33 can be adjusted to vary the position of the bimetal element 31 relative to the latching end of the trip member 65 to thereby vary the thermal tripping time of the breaker.

The invention provides a circuit breaker in which the movable contact member. is biased at both ends by spaced springs one of which springs is normally stronger than the other and biases the movable contact member to the closed position. The trip device functions in response to overload currents to effect a reduction of the tension of the normally stronger spring to permit the other spring to move the contact bar to the open position. The parts of the operating mechanism are assembled in the open side of the housing and are supported by the housing and the cover without any of the parts of the operating mechanism being positively fastened to the housing, the housing and cover being the sole support for the parts.

Having described the invention in accordance with the patent statutes, it is to be understood that various changes and modifications may be made therein without departing from some of the essential features of the invention.

We claim as our invention:

1. A circuit breaker comprising a stationary contact, a movable contact bar having a movable contact rigid therewith for cooperating with said stationary concontact bar, a first spring connected to normally bias said contact bar about a portion of said movable operating lever in opening direction, a second spring connected to normally bias said contact bar about said portion of said movable operating'lever in closing direction, said second spring being efiectively stronger than said first spring to normally maintain said contact bar in the closed position and to provide contact pressure in the closed position of said contact bar, and a trip device operable to effect a reduction of the effective strength of said second spring to permit said first spring to move said contact bar to the open position.

2. A circuit breaker comprising relatively movable contacts, a contact bar having said movable contact on one end thereof and movable to open and close the circuit, an operating lever movable to an open position and to a closed position to efi'ect opening and closing movement of said contact bar, a releasable trip member, a first spring connected under tension to one end of said contact bar and to said trip member normally biasing said contact bar about said operating lever to the closed position, a second spring connected to the other end of said contact bar normally biasing said contact bar in opening direction, said first spring normally applying a greater force to said contact bar than said second spring to hold said contact bar in said closed position, and a trip device operable to release said trip member to thereby reduce the force applied by said first spring to said contact bar and permit said second spring to move said contact bar to the open position.

3. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an operating lever having spaced projections thereon and movable to efiect opening and closing movement of said switch member, a first spring connected to normally bias said switch member in closing direction about one of said projections, a second spring connected to normally bias said switch member in opening direction about said one projection, said first spring normally applying a greater elfective force to said switch member than said second spring to maintain said switch member in closed position, and a trip device operable in response to abnormal conditions to reduce the eliective force applied by said first spring to said switch member to permit said second spring to move said switch member to open position.

4. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an operating lever having spaced projections thereon and movable to efiect opening and closing movement of said switch member, a closing spring connected to bias said switch member in closing direction about one of said projections, an opening spring connected to bias said switch member in opening direction about said one projection, said closing spring normally applying a greater torque to said switch member than said opening spring to maintain said switch member in closed position, and a trip device operable in response to abnormal conditions to reduce the torque applied by said closing spring to said switch member to permit said opening spring to move said switch member to open position, said switch member when moved to said open position engaging another of said projections and moving said operating lever to a trip indicating position.

5. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an, operating lever having spaced projections thereon and movable to effect opening and closing movement of said switch member, a first spring having one end attached to one end of said switch member biasing said switch member about one of said projections to the closed position, a releasable member having the other end of said first spring attached thereto, a second spring having one end attached to the other end of said switch member biasing said switch member in opening direction, a trip device normally releasably restraining said releasable member in operative position wherein it causes said first spring to normally apply a greater effective force on said switch member than said second spring to maintain said switch member in closed position against the bias of said second spring, and a trip device responsive to abnormal conditionto release said releasable member to thereby decrease the efiective force of said first spring and per- '5 mit said second spring to vmove said switch members to the open position.

6. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an operating lever having spaced projections thereon and movable to efiect opening and closing movement of said switch member, a first spring having one end attached to one end of said switch member biasing said switch member about one of said projections to the closed position, a releasable member having the other end of said first spring attached thereto, a second spring having one end attached to the other end of said switch member biasing said switch member in opening direction, a trip device normaly releasably restraining said releasable member in operative position wherein it causes said first spring to normally apply a greater effective force on said switch member than said second spring to maintain said switch member in closed position against the bias of said second spring, and a trip device responsive to abnormal conditions to release said releasable member to thereby decrease the efiective force of said first spring and permit said second spring to move said switch member to the open position, and a portion of said operating lever engaging and resetting said releasable member to thereby restore said first spring to its normal effective force.

7. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an operating lever having spaced projections thereon cooperating with said switch member to effect manual opening and closing movement of said switch member, extensions on said operating handle disposed one on each side of said switch members for preventing lateral movement of said switch member, a first spring attached to one end of said switch member normally biasing said switch member about one of said projections to closed position with a predetermined force, a second spring attached to the other end of said switch member biasing said switch member about said projection in opening direction with a force less than the predetermined force of said first spring, a re leasable member attached to said first spring, and a trip device operable to release said releasable member to thereby reduce the force of said first spring and permit said second spring to move said switch member to open position.

8. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an operating lever having spaced projections thereon cooperating with said switch member to effect manual opening and closing movement of said switch member, extensions on said operating handle disposed one on each side of said switch member for preventing lateral movement of said switch member, a pin on said switch member cooperating with a slot in said housing to prevent longitudinal movement of said switch member, a first spring attached to one end of said switch member normaly biasing said switch member about one of said projections to closed position with a predetermined eifective force, a second spring attached to the other end of said switch member biasing said switch member about said projection in opening direction with a force less than the eifective force of said first spring, a releasable member attached to said first spring, and a trip device operable to release said releasable member to thereby reduce the effective force of said first spring and permit said second spring to move said switch member to open position.

9. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an operating lever having spaced projections thereon and movable to an on and to an oif" position to elfect opening and closing movement of said switch member, a first spring connected to normally bias said switch member about one of said projections on said operating lever to closed position with a predetermined effective force in the on position of said operating lever, a second spring normally biasing said switch member in opening direction with a lesser force than said first spring, said operating lever when moved to the off position moving said one projection to a position to reduce the effective force of said first spring and permit said second spring to move said switch member to said open position.

10. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, an operating lever having spaced projections thereon and movable to an on and to an 01f position to effect opening and closing movement of said switch member, a first spring connected to normally bias said switch member about one of said projections to closed position with a predetermined torque in the on position of said operating lever, a second spring normally biasing said switch member in opening direction with a lesser :torque than said first spring, said operating lever when moved to the off position moving said one projection to a position to reduce the torque applied by said first spring and permit said second spring to move said switch member to said open position, and a trip device operable in response to abnormal conditions to reduce the torque applied by said first spring to permit said second spring to move said switch member to open position.

11. A circuit breaker comprising relatively movable contacts, a movable switch member movable to open and close said contacts, a pivoted operating lever having projections thereon and movable to an on position and to an otf position to effect opening of said contacts, one of said projections in the "on" position of said operating lever engaging and supporting said movable switch member in the closed position, a releasable member, a first spring connected under predetermined tension between said switch member and said releasable member biasing said switch member about said one projection to the closed position, a second spring conected under tension to said switch member biasing said switch member in opening direction, said first spring normally having a greater biasing force than said second spring to maintain said switch member closed against the bias of said second spring, said operating lever when moved to said 01f position moving said projection to a position to permit said second spring to actuate said switch member to the open position, a trip device normally releasably restraining said releasable member in a position to maintain said predetermined tension on said first spring, said trip device being operable in response to abnormal circuit conditions to release said releasable member to thereby reduce the tension of said first spring and permit said second spring to move said switch member to open position.

12. A circuit breaker comprising a stationary contact, a movable contact bar having a movable contact thereon for cooperating with said stationary contact to open and close the circuit, an operating lever movable to effect opening and closing movement of said contact bar, a first spring at one end of said contact bar normally biasing said contact bar about a first fulcrum with a predetermined effective force to normally maintain said contact bar in closed position and to provide contact pressure, a second spring at the other end of said contact bar normally biasing said contact bar to open position with a lesser eifective force than said first spring, and said operating lever being movable to a position to permit movement of said contact bar about a second fulcrum whereby the eifective force of said second spring is increased so that said second spring moves said contact bar to the open position.

13. A circuit breaker comprising a stationary contact, a movable contact bar having a movable contact thereon for cooperating with said stationary contact to open and close the circuit, an operating lever movable to an open position and to a closed position to effect opening and closing movement of said contact bar, a first spring connected to normally bias said contact bar about a first fulcrum on said operating lever with a predetermined torque to provide contact pressure in the closed position of said contact bar, a second spring connected to normally bias said contact bar in opening direction with a lesser torque than said first spring, and movement of said operating lever to said open position moving said first fulcrum to permit movement of said contact bar about a second fulcrum whereby the torque applied by said second spring is increased so that said second spring moves the contact bar about said second fulcrum to open position.

14. A circuit breaker comprising a stationary contact, a movable contact bar having a movable contact thereon cooperating with said stationary contact, an operating lever movable to an open position and to a closed position to eifect opening and closing movement of said contact bar, a first spring connected to normally bias said contact bar about a fulcrum on said operating :7 S lever to closed position1 with a predetermined effective References Cited in the file of thisv patent moment arm, a secon spring counecte to normally bias said contact bar in opening direction, and said op- UNITED STATES PATENTS crating lever when moved to said open position moving Number Name Date said fulcrum to an inefiective position permitting said 5 2,328,458 Jackson et a1 Aug. 31, 1943 contact bar to move about a second fulcrum whereby 2,361,564- Platz Oct. 31, 1944 the moment arm of said first spring is reduced to per- 2,443,090 Wise June 8, 1948 mit said second spring to move the contact bar about said second fulcrum to the open position. 

